Warnings for Multiple Exposures

Current regulatory requirements and chemical product warnings, for the most part, address the single chemicals in the product being addressed. There are no requirements for the consideration of the context in which the product can be reasonably expected to be used and the multiple exposures that may ensue. Benzene use provides an example. 

The current allowable airborne exposure level for benzene as an impurity in solvent mixtures is 0.1 %. Benzene is also readily absorbed through the skin and those having dermal contact with solvents used for cleaning that contain 0.1% benzene contamination (the current allowable level) can be subjected to significant benzene absorption. In a study of workers who cleaned their hands with such solvents, the risk for leukemia was increased by 42%J161 This example points out the need for a more stringent regulation for the allowable concentration of benzene in solvent mixtures. The authors of the study cited recommend that the allowable level be reduced from 0.1 % to 0.01%. Other studies have made similar recommendations. 1171 

It should be noted that workers exposed to benzene by dermal contact also may inhale vapors and thus receive a dual exposure. The air in many polluted areas often contains significant benzene levels as a result of the combustion of petroleum fuels. The ambient air over Los Angeles, California, in the decade 1990-2000, for example, typically contained greater than 1.0 ppm benzene.I18 Tobacco smokers and those exposed to secondhand (or environmental) smoke are further exposed to benzene. It is reasonable to anticipate that benzene-containing solvents will be used in urban and industrial areas where the air is polluted with benzene and that smokers will be among those who use such solvents. Such conditions further dictate the need for lowering the allowable benzene concentration in solvents. 

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